Coin level indicator for coin operated apparatus



Jan. 27, 1970 c. o. HAYS ETAL 3,492,428

COIN LEVEL INDICATOR FOR COIN OPERATED APPARATUS Filed Sept. 8, 1966 2Sheets-Sheet l m #:1 W6 A m m 5 m J P K m m L m Mm N LC H E!\ WE y EA NLME IF R L L R ME 07K C0 GD. HAYS /Nl EN7DR 71E. RED/CK ATTORA/EV Jan.27, 1970 c. o. HAYS T L 3,492,428 7 -COIN LEVEL INDICATOR FOR COINOPERATED APPARATUS Fil'ed Sept. 8, 1966 2 Sheets-Sheet 2 United StatesPatent Ofitice 3,492,428 Patented Jan. 27, 1970 3,492,428 COIN LEVELINDICATOR FOR COIN OPERATED APPARATUS Carroll D. Hays, Brownsburg, andThomas E. Redick,

Indianapolis, Ind., and Rembert R. Stokes, Middletown, N.J., assignorsto Bell Telephone Laboratories, Incorporated, Murray Hill, BerkeleyHeights, N.J., a corporation of New York Filed Sept. 8, 1966, Ser. No.577,958 Int. Cl. H04m 17/02 US. Cl. 1796.4 8 Claims ABSTRACT OF THEDISCLOSURE This invention relates to telemetering systems and moreparticularly to arrangements for sensing and indicating to a remotelocation a particular level of collection in the cash receptacle of coinoperated apparatus.

A disadvantage share by virtually all coin operated devices from vendingmachines to telephones is that unpredictable usage patterns make itimpossible to establish a fully eflicient schedule of cash collections.Collections made too frequently fail to take advantage of the fullcapacity of the cash receptacle and accordingly, are economicallywasteful in terms of man hours spent by the human route collectors. Onthe other hand, collections made too infrequently are at least equallyundesirable in that full cash boxes may result in damaged or inoperativeequipment that causes customer dissatisfaction and loss of revenue.

It has long been realized that the problems indicated could be metreadily by the use of a telemetering system that has the capability ofSensing when collected coins fill some preselected substantial fractionof the cash receptacle and the capability of transmitting to some remotecontrol point a suitable signal indicia of this condition. With mostcoin operated apparatus the cost of providing a communication channelmakes any form of a telemetering system prohibitively expensive. In thecase of coin telephones, however, a communication channel in the form oftelephone lines is available at no extra cost. Understandably, asubstantial portion of the prior art in this area lies in the field ofcoin operated telephones. Patent 1,571,692 issued to P. G. T.DeVilliers. Feb. 2, 1926 is illustrative.

A number of prior art arrangements rely on completing a conducting pathto ground through the accumulated coins as soon as the coins reach somepredetermined level in the box. It is known, for example, to employ aconductor in the form of a probe which is mounted through one side ofthe cash box and which protrudes into the approximate center of the box.When the apex of the normally conical coin stack contacts the probe, ashort circuit path to ground, which may be the bottom of the box, iscompleted through the coins. The coins tend to shift around slightly,however, with each additional deposit. This condition, coupled with thecomparatively very limited conducting area of the probe, tends to makethe short circuit path intermittent for some undertermined period andtherefore unreliable as an indicator of the level of the accumulatedcoins. Additionally, one or more coins at the top of the stack are oftensupported in an edgewise position by leaning against the probe, causinga premature signal. Subsequent deposits tend to knock the leaning coinsdown, adding further to the unreliability of the shorting path.

Accordingly, a broad object of the invention is to increase theefiiciency of collecting accumulated deposits of coins from coinoperated apparatus.

A more specific object is to increase the reliability of coin leveldetecting arrangements.

Another object is to avoid any reduction in the physical security of acoin receptacle resulting from the installation of a coin leveldetecting system.

These and other objects are achieved in accordance with the principlesof the invention by the utilization of a substantially fiat dual elementsensor plate that includes a signal plate and a ground plate separatedby an insulating plate. The ground plate is clipped flat against therear wall of the coin receptacle and is in electrically conductivecontact with the receptacle cover. The cover in turn bears against agrounded portion of the surrounding vault. The ground plate extends intothe lower portion of the coin receptacle and its relatively largesurface is exposed to contact with deposited coins as soon as the coinstack starts to build. The signal plate and insulating plate are affixedto the upper portion of the ground plate at a preselected level andtriggering of a monitoring circuit occurs whenever the coin level issufiicient to establish a short circuit path through the coins from thesignal plate to the ground plate.

One key aspect of the invention relates to the size of the two coincontacting members, the signal plate and the ground plate, which cover asubstantial portion of one wall of the coin receptacle in contrast toprior art arrangements that utilize cylindrical probes. Not only iscontact reliability enhanced by increasing the contact area with thedeposited coins by several orders of magnitude, but also, the reductionin coin storage capacity attendant to the use of probes is virtuallyeliminated.

In accordance with a particular feature of the invention the lower edgeof the signal plate is bent outwardly forming a ledge to facilitate goodcontact pressure between the coins and the signal plate. The undersideof the ledge is protected from conducting contact with the coin stack bya similar ledge formed by the insulating plate. As a result, signalingreliability is enhanced when the coin level exceeds the preselectedlevel and complete protection is provided against those temporary andtherefore unrealiable conducting paths that might otherwise beestablished between the signal plate and the ground plate byedge-balanced or leaning coins.

Another feature of the invention pertains to the relation between thecoin level detector apparatus and the coin telephone control circuitrythat ensures complete isolation of the detector apparatus wheneveruncollected coins are present in the coin hopper. This arrangementavoids the possibility of any interference with normal coin control bythe coin level detector apparatus.

One particularly attractive feature relates to the ease with which aconventional coin telephone may be moditied to include a coin leveldetection arrangement in accordance with the invention. The necessaryelements may be supplied in kit form and the assembly and installationcan readily be accomplished within a few minutes with minimum technicalskill.

The principles of the invention as well as additional objects andfeatures thereof will be fully apprehended from the following detaileddescription of an illustrative embodiment and from the drawing in which:

FIG. 1 is a simplified schematic circuit diagram of a coin telephonethat includes a coin level detector arrangement in accordance with theinvention;

FIG. 2 is a perspective view of a coin level detecting arrangementassembled in a coin receptacle;

FIG. 3 is a perspective view of the dual element sensor plate;

FIG. 4 is a side view of the sensor plate shown in FIG. 3;

FIG. 5 is a side view partially in cross section of the cover of thecoin receptacle, the top of the coin receptacle vault and certainstructural elements of the coin level detecting arrangement afiixedthereto;

FIG. 6 is a side view of a portion of the sensor assembly of FIG. 3showing coins in the receptacle before contact is made with the signalplate; and

FIG. 7 is a side view of a portion of the sensor assembly of FIG. 3showing coins in the receptacle after contact is made with the signalplate.

The simplified schematic telephone circuit diagram of FIG. 1 shows aconventional telephone speech network 10 connected across subscriberlines R and T with a line relay LR in the ring lead R. A path to groundfrom the network 10 is provided through the coin relay CR, the armatureactuated switching member CR of the coin relay, the break contact BK,resistor R1 and the coin level detector 11. In accordance with theinvention, the coin lever detector 11 completes the path to ground asdescribed only when the level of coins collected in the coin receptacleexceeds some predetermined height. Irrespective of whether the coins inthe coin receptacle exceed the predetermined height, however, theoperation of the hopper trigger contact HTl, which is acuatedconventionally by the deposit of any coin, shunts the coin leveldetector 11 and its associated resistor R1, thus, in effect, removing itfrom the circuit. The path to ground through the operated hopper triggercontact HT1 is detectable by the operator in the central office and isan indication that a coin or coins have been deposited in the hopper andthat neither collection nor refund has been elfected.

When the coin relay CR is operated by a suitable pulse from the centraloflice to efiect either coin collection or coin refund, the hoppertrigger contact H'Il is reset in a well-known manner by associatedapparatus, not shown; the path shunting the coin level detector 11 andresistor R1 is opened and the central otfice is once again able todetermine whether or not the coin collection level in the coinreceptacle has been exceeded by the presence or absence of a circuit toground through the coin level detector 11.

Resistor R1 limits the flow of current to ground and effects adetectable voltage drop when the path to ground is completed through thecoin level detector 11. Resistor R2 is conventional and its purpose isto limit the current flow to ground when the coin relay CR is shunted bythe path through the coin relay armature switch CR and its make contactMK. In summary, from a circuit standpoint, a conventional coin telephonestation circuit in order to utilize a coin level detecting arrangementin accordance with the invention, need only be modified by the additionof the coin level detector 11 and resistor R1 in the manner indicated inFIG. 1.

The key element of a coin level detector in accordance with theinvention is a dual element sensor plate 301 shown in FIG. 3. The sensorincludes an electrically conducting ground plate 302, an electricallyconducting signal plate 303 and an insulating plate 304 sandwichedbetween. The lower edge of the signal plate 303 is bent outwardly toform a substantially horizontal ledge 303A. A similarly protruding ledge304A is formed from the lower portion of the insulating plate 304. Itshould be noted in particular that the insulating ledge 304A extendsslightly beyond the ledge 303A of the signal plate as shown clearly inFIGS. 6 and 7.

The signal plate 303 also includes a slotted tab 305 partially bent overan insulating tab 306 that limits the distance that the tab 305 may bedepressed. The upper edge of the signal plate 303 is positioned byinsulating clips 307307, and the entire sensor assembly is fixed rigidlytogether by fasteners 308308. The upper portion of the ground plate 302terminates in a pair of integral clip members 309309.

As shown in FIG. 2 the clips 309309 permit the sensor assembly 301 to beafiixed simply yet securely to the rear wall of the coin receptacle 200.In FIG. 2 the cover 201 of the coin receptacle 200 is shown in the openposition pivotally secured to the coin receptacle 200 by tabs 203-203inserted in accommodating slots in the upper portion of the rear wall ofthe coin receptacle. When the cover 201 is closed, electrical contact ismade between the cover and the clips 309-309. When the coin receptacle200 is inserted in its protective enclosing vault in the conventionalmanner, the receptacle cover 201 is in electrically conducting contactwith the vault 502, a portion of which is shown in FIG. 5. The vault 502is a main structural part of the telephone and accordingly remains atground potential.

OPERATION From the foregoing it is seen that in the absence of coins inthe receptacle 200, the ground plate 302 is at ground potential and iscompletely insulated from the signal plate 303. As the level of coins inthe receptacle 200 increases as additional coins are deposited, the topof the coin stack eventually contacts the insulating ledge 304A as shownin FIG. 6. Conducting contact with the signal plate 303 cannot occur,however, until the coins exceed the height of the ledge 303A at whichpoint they form a conducting path between the ground plate 302 and thesignal plate 303 as shown in FIG. 7. Once such contact is made, it ismaintained inasmuch as intermittent or temporary contact between thesignal plate and the coin stack that might otherwise be caused byedgebalanced or temporarily leaning coins is avoided in accordance withthe invention by the relative positioning of the ledges 304A and 303A asshown in FIG. 6. The ledge 303A serves an additional function in thatits horizontal surface ensures the aid of gravity in maintaining goodelectrical contact with the coins in physical contact therewith as shownin FIG. 7.

The final extension of ground potential to the terminal of resistor R1by the coin level detector 11, as shown in FIG. 1, may be traced in FIG.5. A conducting path is formed from the tab 305 of the signal plate 303to a lug 202 which is in contact therewith when the cover 201 of coinreceptacle 200 is closed. The lug 202 is mounted in an accommodatinghole in cover 201 but is insulatedly separated therefrom. A conductingspring 505 is in electrically conducting contact with the top of the lug202, and is insulated from the top of the vault by an insulating strip501. A weld stud 504 attached to the conducting spring secures thespring 505- and strip 501 to the underside of the top of the cointelephone vault 502 and provides electrical continuity to a smallnonconducting circuit board member 503 which is held in place on theupper surface of the vault 502 by the stud 504 and its associated nut506. The resistor R1 is mounted on this terminal board and its lead isin electrical contact with the stud 504.

It is to be understood that the embodiment described herein is merelyillustrative of the principles of the invention. Various modificationsthereto may be made by persons skilled in the art without departing fromthe spirit and scope of the invention.

What is claimed is:

1. A coin operated telephone station comprising, in combination,

a receptacle for deposited coins,

a speech network connectable across a telephone line,

a source of reference potential,

first circuit means in said receptacle for completing a first electricalpath from said reference potential through deposited coins to saidnetwork and thence to said telephone line whenever the coins in saidreceptacle exceed a preselected level, and

second circuit means including a hopper trigger contact responsive tothe deposit of coins for completing a second electrical path from saidreference potential to said network and thence to said telephone line,

said second circuit means shunting said first circuit means wheneversaid hopper trigger contact is in the operated condition,

thereby effectively avoiding any possible interference with the coincontrol functions of said station by said second circuit means.

2. A coin operated telephone station comprising, in

combination,

a speech network connectable across a telephone line,

a source of reference potential,

first circuit means responsive to the deposit of a preselected volume ofcoins for completing a conductive path from said source to said networkand hence to said telephone line,

second circuit means including a hopper trigger contact responsive tothe deposit of any coin for completing a conductive path to said networkand hence to said telephone line,

said second circuit means shunting said first means whenever said hoppertrigger contact is in the operated condition,

said hopper trigger contact remaining in the operated condition afterthe deposit of a coin or coins until the refund or collection of saidlast named coin or coins,

thereby avoiding any possible interference with said second circuitmeans by said first circuit means.

3. Apparatus in accordance with claim 2 including a coin receptacle,

said first circuit means comprising, in combination,

a first electrically conducting plate member afiixed fiat against theinside of one side of said receptacle and extending into the lowerportion thereof,

an insulating plate covering the upper portion of said first plate,

first means connecting said first plate to said reference potential,

21 second electrically conducting plate afiixed to said insulatingplate,

second means connecting said second plate to said network,

whereby deposited coins in said receptacle that reach the level of thelower portion of said second plate complete a conducting path betweensaid first and second plates.

4. Apparatus in accordance with claim 3 wherein the lower edge of saidinsulating plate and the lower edge of said second pltae are bentoutwardly to form a relatively narrow shelf,

the insulating plate portion of said shelf protruding beyond the secondplate portion of said shelf,

whereby said insulating plate portion of said shelf avoids intermittentconducting paths that might otherwise be formed by temporarily edge-onor leaning coins,

and whereby said second plate portion of said shelf ensures gravityenhanced electrical contact between said shelf and coins restingthereon.

5. Apparatus in accordance with claim 3 wherein said second connectingmeans includes at least one resisttive element.

6. Apparatus in accordance with claim 3 wherein the upper portion ofsaid first plate terminates in at least one clip member that securessaid first plate to said side of said receptacle.

7. Apparatus for electrically detecting the level of coins in a coincollection receptacle comprising, in combination,

a source of reference potential,

a first electrically conductive plate exposed to conductive contact withcoins in said receptacle below a preselected level,

a second electrically conductive plate exposed to conductive contactwith coins in said receptacle above said level,

said plates normally being insulatedly separate,

whereby, an electrically detectable conductive path between said platesis established through deposited coins whenever the coins in saidreceptacle exceed said preselected level,

wherein the lower edge of said second plate forms a shelf portionextending out from the plane of said plates,

insulating means covering the underside of said shelf portion andextending beyond said shelf portion,

thereby precluding intermittent and unreliable conducting paths betweensaid plates that might otherwise be formed by temporarily edge-balancedor leaning coins.

8. A coin level detecting arrangement for coin operated apparatus,comprising, in combination,

a box-like coin receptacle,

a first conductive plate member vertically disposed in said receptacle,

a second conductive plate member insulatedly separated from said firstmember and vertically disposed in said receptacle,

said first member being exposed to electrically conductive contact withcoins in said receptacle up to a predetermined level,

said second member being exposed to electrically conductive contact withcoins in said receptacle above said level,

means connecting one of said members to a reference potential,

whereby coins in said receptacle complete an electrically detectableconductive path to said reference potential whenever the level of coinsin said receptacle exceeds said level, the lower edge of said secondmember being formed into a substantially horizontal ledge, at least aportion of the underside of said ledge being insulatedly protected fromconductive contact with deposited coins,

thereby preventing completion of said conductive path by coins balancededge-on or leaning against the underside of said ledge.

References Cited UNITED STATES PATENTS 1,571,962 2/ 1926 DeVilliers340-421 3,091,663 5/1963 Stokes 179-63 3,112,366 11/1963 Gibbs 1796.4

KATHLEEN H. CLAFFY, Primary Examiner J. S, BLACK, Assistant Examiner

